Cannot specify child attributes in the columnset for Retrieve - dynamics-crm

Question

In attempting to merge contacts in Microsoft CRM, I am using the following code -
//c1ID and c2ID are GUIDs of duplicated contacts.
EntityReference target = new EntityReference();
target.LogicalName = Contact.EntityLogicalName;
target.Id = c2ID;
MergeRequest merge = new MergeRequest();
// SubordinateId is the GUID of the account merging.
merge.SubordinateId = c1ID;
merge.Target = target;
merge.PerformParentingChecks = true;
Contact updater = new Contact();
Contact updater2 = new Contact();
updater = (Contact)xrmSvc.ContactSet.Where(c => c.ContactId.Equals(c1ID)).First();
updater2 = (Contact)xrmSvc.ContactSet.Where(c => c.ContactId.Equals(c2ID)).First();
MergeResponse mergedR = (MergeResponse)xrmSvc.Execute(merge);
When I try my Execute call here,I get this error -
Cannot specify child attributes in the columnset for Retrieve. Attribute: owneridname.
Am I not setting something correctly?

Answer 1

Having updatecontent does not change the issue. In fact, I get the error on lookups entered into the updatecontent. I find you have to build new entityreferences:
if (match.Contains("new_mostrecentcampaign"))
master["new_mostrecentcampaign"] =
new EntityReference(match.GetAttributeValue<EntityReference>("new_mostrecentcampaign").LogicalName
, match.GetAttributeValue<EntityReference>("new_mostrecentcampaign").Id);
...
Merge.UpdateContent = master
...

Answer 2

I realize this is a pretty old question, but for those of you who have run into the same issue in 2021 and beyond, here's the reason this error happens.
TL;DR: Ensure the EntityReference values for the attributes does not specify the Name property.
Explanation:
Everything that gets added to the Entity set to UpdateContent will be applied to the Target contact. When programmatically executing a MergeRequest within a plugin/workflow, the attributes of the UpdateContent get applied (as desired).
Where this breaks down is for EntityReference value types (lookups). The internal Microsoft code that performs this operation tries to interpret all properties of the EntityReference object, including Name.
So when the existing values from the SubordinateId contact are pulled using IOrganizationService.Retrieve (to dynamically get the latest version), the Name property is automatically set for those lookup attributes (the child record). This operation is not valid, even though it's not the user code that's directly executing it.
This brings us full circle to explain the original error:
Cannot specify child attributes in the columnset for Retrieve

Answer 3

I wish I had some documentation for this, but although the official documentation notes that the UpdateContent is optional, experience proves that it is in fact necessary. In the MergeRequests I've tested, I always include that property in the request, and there's a post in the MSDN forums for Dynamics 3.0 that suggests the same.
In fact, when I try to merge two contacts in my org without UpdateContent assigned, I actually get a FaultException saying the following:
Required field 'UpdateContent' is missing
Even though the documentation says it's optional!
So I'd suggest populating the UpdateContent property with something as in the below and see if that works:
var merge = new MergeRequest
{
// SubordinateId is the GUID of the account merging.
SubordinateId = c1ID,
Target = target,
PerformParentingChecks = true,
UpdateContent = new Contact()
};